by Susan Little DVM, Dipl ABVP (Feline)

Constipation is the infrequent and difficult evacuation of feces with retention of feces within the colon and rectum. Obstipation is intractable constipation. The typical feline patient is middle-aged and male. Many cats have one or two episodes of constipation without any further problems. However, chronic

constipation and obstipation may result in megacolon where a dilated large bowel is poorly responsive to therapy. Cats with idiopathic megacolon have generalized dysfunction of colonic smooth muscle. Some of the more common underlying causes of constipation include:

Drugs: especially opiates, anticholinergics, sucralfate.

Behavioral: Stressors, e.g., changes in the home or routine Litter box aversion.

Difficulty defecating: Pain in rectal or perineal area.

Orthopedic problems: arthritis.

Neurologic problems.

Fecal factors: Excessive fecal bulk

Colon factors: Mass: intra-or extra-luminal, Obstruction due to narrowed pelvic canal, e.g. from previous trauma

Miscellaneous: Dehydration, e.g. due to chronic renal disease .

Idiopathic megacolon In one review, 62% of cases were due to idiopathic megacolon and 23% to pelvic canal narrowing.S Whenever possible, the underlying cause should be identified and corrected.

The clinical signs of constipation are typically obvious to the owner, such as tenesmus, and scant hard dry feces, sometimes with blood. However, cats will also strain in the litter box due to lower urinary tract obstruction and owners may misinterpret this as due to constipation. Occasionally, constipated cats will have intermittent diarrhea as the colon is irritated due to hard dry fecal matter. Other clinical signs are non-specific, such as vomiting, inappetence and lethargy.

Physical examination confirms the presence of large amounts of feces in the colon sometimes accompanied by abdominal pain. The colon often palpates as a long firm tube or feces may be palpated as discrete concretions. A careful evaluation (e.g., musculoskeletal system, caudal spinal cord function, anorectal area) should be made for underlying causes. A rectal exam should be performed, under sedation if necessary, for masses, pelvic fracture malunion and anal gland abnormalities. A minimum database (CBC, serum chemistries/electrolytes, urinalysis) should be assessed, especially to determine hydration and electrolyte status and identify underlying diseases such as chronic renal disease. Survey abdominal radiographs are useful to confirm the diagnosis and assess severity as well as to evaluate for potential underlying causes, such as previous pelvic trauma and arthritis. The diameter of the colon on a lateral view should be approximately the same length as the body of the 2nd lumbar vertebra.10 Enlargement of the colon beyond 1.5 times the length of the body of the 5th or 7th lumbar vertebra has been proposed as indicating chronic dysfunction and megacolon.»-10 One study of 11 cats with megacolon found the mean diameter of the colon was 2.7 times greater than the length of the 7th lumbar vertebra (median: 2.4, range 1.8-3.3). In some cases, further diagnostics such as a barium enema or colonoscopy may be warranted.

The first step in management is correction of dehydration with intravenous fluid therapy followed by removal of obstructing feces. One or two doses of a 5 ml microenema containing sodium lauryl sulfoacetate (MicroLax) is easily administered and will usually produce results within 20-30 minutes in mildly affected cats. Obstipated cats will require warm water or isotonic saline enemas (5-10 ml/kg). Safe additions to the water include mineral oil (5-10 ml/cat), or docusate (5-10 mL/cat). Soaps or detergents may be irritating to an already compromised colonic mucosa. Lactulose solution can also be administered as an enema (5-10 ml/cat). Sodium phosphate containing enemas must not be used as they can induce life-threatening hypernatremia, hyperphosphatemia and hypocalcemia in cats. Enemas are administered slowly with a lubricated 10-12 French feeding tube. In severe cases, manual manipulation of the feces via abdominal palpation or per rectum (manual disimpaction) under general anesthesia with endotracheal intubation (in case of vomiting) is also required. In these cases, opioids should be administered for pain relief.

An alternative to enemas is administration of an oral polyethylene glycol (PEG 3350) solution (e.g., CoLyte, GoLytely). A nasoesophageal tube is placed and the solution is given as a slow trickle (6-10 ml/kg/hour) over 4-18 hours. Defecation usually results in 6-12 hours. In a retrospective study of 9 cats, median time to defecation was 8 hours and the median total dose of PEG 3350 was 80 ml/kg.?

No adverse effects were noted.

In addition to management of any underlying conditions, long term medical treatment involves a combination of prokinetic agents, laxatives and dietary therapy. Cisapride stimulates contraction of feline colonic smooth muscle.“ A typical starting dose is 2.5 mg/cat BID, PO and it is better absorbed when given with food. Doses up to 7.5 mg/cat, TID have been reported. The drug is only available from compounding pharmacies in most countries. It has been withdrawn from the human market due to the occurrence of life-threatening arrhythmias in predisposed individuals (not known to occur in cats). It may be prudent to advise clients handling cisapride to wear gloves. Hyperosmotic laxatives include lactulose and PEG 3350; they stimulate colonic fluid secretion and propulsive motility. The dose of lactulose solution is 0.5 mL/kg, PO, BID-TID. Lactulose is also available as crystal meant to be mixed in liquids for human use (Kristalose). A suggested dose is 3/4 tsp. BID with food. PEG 3350 is available as a powder meant to be mixed in liquids for human use (MiralAX). A suggested dose for cats is 1/8 to 1/4 tsp. BID in food.

Dietary therapy has included the use of high fiber diets (>20% on as fed basis) and low residue diets. Increased dietary fiber increases the production of short chain fatty acids which stimulate feline colonic smooth muscle contraction. Dietary fiber is also a bulk laxative and will increase fecal bulk, which will not be beneficial for all patients. Feeding a canned diet is often recommended to reduce fecal bulk and to ensure adequate water intake and hydration. Psyllium powder can be mixed with canned food at 1-4 tsp. SID-BID. A certain amount of trial and error is necessary to determine the best diet type for an individual patient.

Recently, a moderate fiber, psyllium-enriched dry extruded diet was introduced for management of gastrointestinal conditions in cats (Royal Canin Gastro Intestinal Fiber Response). In an uncontrolled study by the manufacturer, 66 cats with recurrent constipation were successfully treated with the Fiber Response diet. The diet was well tolerated and palatable. Most cats improved within 2 months and were either maintained on diet alone or with decreased doses of cisapride and lactulose than previously used.

It is also important to ensure adequate water intake by various methods, such as feeding canned diets. Most water bowls designed for cats are too small; cats dislike having their whiskers touch the side of containers. Dog water bowls are larger and more appropriate. Other methods for increasing water intake include:

Mix water with dry diets 1:1 Flavor water with frozen cubes of meat or fish broth Try distilled or filtered water, especially if the tap water supply is heavy in minerals or chlorine Ensure water is fresh every day, and provide multiple water bowls Ensure the water bowls are kept clean

Keep food and water bowls away from the litter box – Feed multiple smaller meals instead of one or two larger meals – Provide a moving source of water such as a pet water fountain

Litter box modification may be helpful for cats with arthritis. Most cat litter boxes are too small and have high sides. A winter boot tray or an under-the-bed type of storage box with low sides is a better alternative to make access easier. The litter box should also be in an accessible but private area, avoiding the need to navigate stairs if possible.

Subtotal colectomy (95-98% excision, with preservation of the ileocolic junction) should be considered for cats refractory to medical and dietary therapy. Long term outcome is considered excellent. Most patients will experience transient diarrhea in the immediate post-operative period (1-6 weeks). In a small number of patients, diarrhea will persist.

1. 57:580, 1996. 

by Susan Little DVM, Dipl ABVP (Feline)

Refers to spay/neuter before the traditional age of six to eight months of age 

• Desirable approach to pet overpopulation control for shelters; enables pre-adoption  altering  
• Pedigreed cat breeders may request early age altering for pet kittens  
• Major North American veterinary organizations have position statements  supporting the concept  

Perceived detrimental effects include:  

1. Stunted growth  
2. Obesity  
3. Behavioural changes  
4. Increased risk of disease, including lower urinary tract disease 

Growth: altering at any age prior to seven months may delay physeal closure and  result in increased long bone length 

1. University of FL (Stubbs et al, 1996): evaluated skeletal growth in cats altered  at seven weeks, seven months and those left intact; delayed closure of the  growth plate of the radius was seen in cats altered at both seven weeks and  seven months of age

2. University of MN (Root el al, 1997): radius length was longer in cats altered at  both seven weeks and seven months versus intact cats 

Obesity: a multifactorial problem involving diet, exercise, age and other factors;  Root et al (1996) showed that altered cats require fewer calories than intact cats  regardless of the age at which they were neutered; male cats altered at both seven  weeks and seven months required 28% less calories than intact male cats; female  cats altered at both seven weeks and seven months required 33% fewer calories than  intact female cats 

Behaviour:  

1. University of FL study (Stubbs et al, 1996): behaviours were similar between  both groups of altered cats; sexually intact cats demonstrated less affection  toward humans and more interspecies aggression 
2. Cornell University study, 1660 cats with median follow up time of 4 years  (Spain et al, 2004): early altered cats showed more shyness and less  hyperactivity than cats neutered after six months of age; early altered male cats  showed less aggression to veterinarians, less urine spraying but more  occurrences of hiding 

3. Mercer University study (Wright, 2001): 127 kittens, split litter design, followed  for one year, no differences in behaviours based on age at altering 
4. Texas A&M Study (Howe et al, 2000): 263 cats (188 altered at under six  months of age), followed for three years, no difference in behaviour problems 

Disease risk:  

1. University of FL, University of MN studies: urethral diameter is not affected by age  at neutering in male cats; feline lower urinary tract disease is caused by a wide  variety of factors, including diet 
2. Cornell University study (Spain et al, 2004): concluded neutering before 5.5 months  of age is not associated with any serious long-term outcomes, showed important  benefits such as less asthma, gingivitis and bite wound abscesses  
3. Texas A&M study (Howe et al, 2000): 263 cats (188 altered at under six months of  age), followed for three years, no increased disease risk as compared to traditional age surgeries  

Anesthesia and Surgery:  

• Pediatric animals distribute and metabolize drugs differently, must be careful with  drug selection and doses  
• Surgical benefits to early age altering:  

1. Less bleeding  
2. Improved visualization  
3. Small size of organs means shorter surgery time 
4. More rapid recoveries, less patient discomfort  
5. Very low complication rate  

• Anesthetic complication rates are low:  

1. Faggella and Aronsohn’s study of 96 kittens reported no complications.  2. Texas A&M University (Howe et al, 1997): 779 shelter cats altered by 4th year  vet students, early age altering did not increase morbidity or mortality during  the intra- or postoperative period (seven days after surgery). Kittens altered at  less than 12 weeks of age actually had a lower postoperative complication rate  (6.5%) than those altered at greater than 23 weeks of age (10.8%).  

Five Rules for Successful Early Age Altering:  

1. Kittens should have complete physical exam; have their first vaccination and  treatment for parasites; postpone surgery if any illness or abnormality found  (including cryptorchidism) 
2. Weigh each kitten to nearest 100 grams, calculate drug doses carefully  3. Combat hypoglycemia: withhold food for only three to four hours; feed a small meal  within one hour of recovery; administer 50% dextrose orally to kittens with prolonged  recoveries or those that will not eat post-op  
3. Decrease stress: keep litters together before surgery in warm, quiet environment;  minimize handling; avoid IV injections; reunite litters as soon as possible after  recovery  
4. Combat hypothermia: insulate against cold surfaces, minimize hair coat clipping,  avoid alcohol in preps, warm prep solutions, monitor rectal temperature, use  supplemental heat sources (warm blankets, hot water bottles, heat lamps, etc)  

us, OH, 2001, pp. 89-90.  

by Susan Little DVM, Dipl ABVP (Feline)

Cats have one blood group system with three blood types: type A, type B, and type AB.

Based on the fact that each individual has two sets of chromosomes, these are due to different forms (alleles) of the same gene.

Thus, only cats carrying two copies of the B allele (genotype homozygous B/B) will have blood type B.

Cats with blood type A may have two copies of the A allele (homozygous AA) or one only copy (heterozygous A/B).

Type A is completely dominant over type B. The third blood type, type AB, appears to be a third form of the same gene, but it is rare.

Type A is the most common feline blood type, present in up to 94%-99% of all domestic shorthair and longhair cats in the United States. 

The frequency of the feline blood groups varies both by breed and by location within the United States. The lowest frequency of type B cats is in the Northeast and North Central/Rocky Mountain regions. Higher frequencies of type B cats are found on the West Coast, peaking in the Northwest with 6% type B cats. 

Siamese cats and related breeds with oriental blood have thus far all been shown to have type A blood. The American Shorthair breed, due to its close relationship to non-pedigreed shorthair cats, is also largely blood type A. However, some other breeds may have astoundingly high numbers of type B cats. The frequency of the blood types does not vary geographically for pedigreed cats.

Frequency of Blood Types in Pedigreed Cats 

(From surveys conducted by the University of Pennsylvania over past 15 years) 

(* indicates breeds with some type AB cats) 

All blood type B cats have strong antibodies against type A blood cells as of three months of age. Blood type A cats generally have very low anti-B antibody titers. It is very important to note that these antibodies are naturally occurring; unlike other species, no previous pregnancy or transfusion is necessary for antibody development. The strong anti-A antibodies in type B cats are important in two situations: blood transfusion reactions following the administration of type A blood to type B cats and neonatal isoerythrolysis (NI or hemolysis of the newborn) due to the newborns’ type A or AB erythrocytes being attacked by the anti-A antibodies in the type B queen’s colostrum. The anti-B antibodies have not been shown to cause NI, but can lead to transfusion reactions if type B blood is given to type A cats. Fortunately these situations can now be avoided. 

Neonatal isoerythrolysis is an immunologic, genetic problem seen in cats, but not dogs. It may be responsible for a large proportion of fading kittens and neonatal deaths in some pedigreed catteries, where the blood type of breeding cats is unknown. NI occurs in blood type A kittens born to a type B queen mated to a type A male. If the tomcat is homozygous (A/A), then all the kittens in the litter will be blood type A and at risk for NI. If the male cat is heterozygous (A/B), then 50% of the offspring would be expected to be heterozygotes with blood type A (genotype A/B) and at risk for NI. This problem can also occur in type AB kittens born to type B queens. 

When kittens nurse from the queen after birth, they receive colostrum that contains antibodies to protect them against common viral infectious diseases, but also antibodies against blood types. The kitten’s digestive tract is able to absorb these antibodies, which pass into their bloodstream, 

for about the first 12-24 hours of life. After that time, “gut closure” occurs in the neonate that prevents absorption of any antibodies. When type A or AB kittens nurse on a type B queen during the first day of life, they receive anti-A antibodies in the colostrum, which in turn get into the blood stream and bind to their red blood cells and destroy them (this is known as isoerythrolysis). 

Clinical signs of NI are variable. Large variations in clinical signs may be due to ingestion of varying degrees of anti-A antibodies in colostrum or as yet undetermined factors. Typically, kittens are born healthy and nurse well. Clinical signs may appear rapidly, with some kittens dying suddenly, within hours. Other kittens will stop nursing within the first three days of life with suggestive signs of failure to thrive, red-brown urine, jaundice, and anemia. As they deteriorate, lethargy, weakness, rapid breathing, a very slow or rapid heart rate, as well as collapse, and eventually death may occur. Some kittens appear to have subclinical disease with no obvious clinical signs. If tested, they may have anemia, however. Surviving kittens may develop damage to the skin of the tail tip up to two weeks later. 

Kittens with signs of NI should immediately be removed from the queen to prevent further absorption of antibodies. They need be removed from the queen for only about the first 24 hours of life since no antibodies are absorbed after that time. The kittens should be foster-nursed by a queen with type A blood if available, or hand-fed a kitten milk replacer. Kittens with severe anemia require a transfusion, but unfortunately these efforts are rarely if ever successful. 

Since the mortality rate with NI is high, the predisposing situation should be prevented by knowing the blood type of breeding cats in breeds with known occurrences of type B blood. In breeds with low type B blood frequencies and catteries with mostly type A breeders, cats that are blood type B may not be used for breeding, in order to minimize future problems with NI. Many breeders are now recording each cat’s blood type on pedigree charts to facilitate breeding decisions. Blood typing can be done in a referral laboratory or by using in-clinic blood typing ®

cards (RapidVet-H , DMS Laboratories, 2 Darts Mill Rd., Flemington, NJ 08822, 1-800-567- 4367). The rare type AB results may be due to autoagglutination or other technical difficulties and should therefore be confirmed in a reference laboratory by a tube assay such as the laboratory at the University of Pennsylvania uses. 

When a breeding between a type B queen and a type A tom must be done, the breeder should endeavor to be present at the birth of the kittens to prevent nursing from the queen. The easiest method is to breed a second queen with type A blood a little earlier, so that the litters from the 2 queens can be exchanged. The second queen’s litter should be over 24 hours old in order to exchange litters. This has the added advantage of potentially allowing the kittens to acquire some passive immunity from the foster queen’s milk. Queen’s milk contains similar quantities of antibodies as in colostrum. The other option is to hand feed the kittens with a commercial milk replacer. Experience suggests that these kittens will do fine, although they will not have any protective antibodies. In either case, the kittens can be returned to their own mother in 24 hours. Some breeders who elect to hand feed milk replacer allow the kittens to stay with the mother for care, but fit the queen with a type of body stocking so that the kittens are unable to nurse. However there are some clever neonates that still find their way to the nipples and suffer the consequences. 

Susan Little, DVM, DABVP (Feline Practice)

Bytown Cat Hospital Ottawa, Ontario, Canada

Feline Pediatrics: How to Treat the Small and the Sick*

Most veterinarians have been presented with kittens that have failed to thrive. These patients are challenging due to their small size, their unfamiliar physiology, and the tendency for their status to deteriorate quickly. The most common general causes of illness and failure to thrive are maternal, gesta-
tional, environmental, genetic, and infectious factors.1,2 In much of the veterinary literature, the neonatal period is defined as the first 4 weeks of life. However, it is clinically useful to consider defined risk periods: the first 4 days of life (when many problems are related to labor and delivery or the environment); between 21 and 28 days of age (when important changes leading to neurologic and behavioral maturation take place); and weaning (4 to 6 weeks of age).

Examination of Neonatal Kittens

There are many clinically relevant physiologic differences between neonatal kittens and adult cats3 (TABLE 1), and very young kittens cannot be approached as small adults. Sick neonates should be examined as soon as possible, using a systematic approach that includes a complete history of the kitten, litter, and queen; examination of the kitten and queen; and diagnostic tests.4,5 Kittens younger than 4 weeks should be examined with the queen present when possible (unless prohibited by the queen’s temperament).Start with a complete medical history for the kitten in question as well as for littermates. It may also be helpful to have a medical history for the queen, if available (e.g., illness, nutrition, vaccina-
tions), and information about the labor and delivery, especially for kittens younger than 2 weeks. If it is not the queen’s first litter, information should also be gathered on previous litters and any previous problems with labor and delivery. Investigate the kitten’s home environment, noting temperature and humidity, sanitation, ventilation, population density, the presence of other pets and small children, and prevalence of infectious diseases and parasites.

Neonates should be handled gently, on a clean, warm surface. Wash your hands and wear gloves. Simple equipment will suffice for neonatal examinations: a gram scale, pediatric rectal ther-
mometer, otoscope with infant cones, penlight, and stethoscope with an infant bell and diaphragm.
Before handling the kitten, observe its body condition and response to the environment, including alertness, posture, loco-motion, and respiratory rate and character. Healthy neonates have a strong suckle reflex that is, by comparison, normally less strong than that of a healthy puppy. Normal body temperature for neonatal kittens is 97°F to 98°F (36°C to 37°C). The rectal temperature rises slowly, reaching 100°F (38°C) by about 4 weeks of age. For the first 2 weeks of life, kittens are essentially poikilothermic and lack a shiver reflex. They gradually become homeothermic after 14 days of age, but are still susceptible to environmental conditions and may become hypothermic easily.

If the birth date is unknown, attempt to establish an estimated age for the kitten by using body weight and inspection of the dentition. The typical kitten birth weight is 90 to 110 g (range: 80 to 140 g), although there is considerable variation by and within breed.6 Normal kittens gain 50 to 100 g/wk (10 to 15 g/d) and should double their birth weight before 2 weeks of age. Low birth
weight is a common cause of mortality, with kittens weighing under 75 g at birth at highest risk. The first deciduous teeth to appear are the incisors and canines at 3 to 4 weeks of age. The premolars erupt at about 5 to 6 weeks of age. The dental formula for deciduous teeth is 2(I3/3, C1/1, P3/2) = 26; there are no deciduous molars.
Developmental milestones may also be helpful in estimating age (TABLE 2), although delayed development may occur in kittens with low birth weight and poor weight gain. Ex-amples include uncoordi-nated walking by 21 days
and coordinated walking by 28 days.Inspect the neonate for
gross anatomic abnormali-ties, such as cleft palate or lip, umbilical hernia or
infection (FIGURE 1), open fontanelle, limb deformi-ties (FIGURE 2), chest wall deformities, and nonpatent urogenital or rectal openings
(FIGURE 3). Kittens younger than about 3 weeks cannot eliminate urine and feces voluntarily. Evaluate a kit-ten’s micturition and defe-cation reflexes using a cotton ball moistened with mineral oil or warm water to stim-
ulate the anogenital area.

Diarrhea is present in about 60% of sick neonatal kittens and may cause sig-nificant fluid loss. Hematu-ria or pigmenturia may be signs of urinary tract infection, trauma, or neonatal isoerythrolysis (FIGURE 4). Neonatal isoerythrolysis may be a common problem in some breeds (e.g., British shorthair, Cornish rex, Devon rex) with a high percentage of individuals with blood type B. BOX 1 lists selected common con-genital defects in neonatal kittens that are apparent around the time of birth.

The eyes should be inspected for abnormalities of the globe or eyelids and for neonatal ophthalmia (before the eyes open) or conjunctivitis (after the eyes open). A menace reflex and pupillary light responses do not appear until 28 days of age or later. A divergent strabismus may be present and is normal until about 8 weeks of age unless hydrocephalus is present. Evaluation of the fundus is difficult until about 6 weeks of age.
The pinnae should be inspected for evidence of trauma, parasites such as ear mites, and skin disease.The ear canals are not easy

How to Treat the Small and the Sick.

Inspect with an otoscope un- til after 4 weeks of age. The neonate’s haircoat should be clean and shiny. Healthy neonatal kittens may have somewhat hyperemic mucous membranes until 7 days of age (although hyperemia may also be a sign of dehydration),whereas sick neo-nates often have pale, gray, or cyanotic mucous membranes. Kittens with cyanotic mucous membranes have a poor prognosis.
The cardiovascular system undergoes dramatic changes as the heart takes over the functions previously performed by the feto-maternal circulation. One important physiologic difference between neonates and adults is the higher neonatal heart rate. The normal neonatal heart rate can be >200 bpm (range: 220 to 260 bpm).
The normal respiratory rate is 15 to 35 breaths/min. Functional murmurs may be present in neonates due to anemia, hypopro-teinemia, fever, or sepsis. Innocent murmurs not associated with disease are more common in puppies than kittens; murmurs present after 4 months of age should be investigated. Congenital heart disease may be associated with murmurs that are loud and
accompanied by a precordial thrill. The most common congenital heart diseases in kittens are tricuspid valve dysplasia and ventricular septal defect.

Abdominal palpation can be performed with care; in the first few days of life, abdominal pressure during palpation may induce regurgitation of stomach contents and aspiration. A full abdomen is normal in a well-fed kitten, but an enlarged abdomen in an ill kitten may indicate aerophagia. The normal liver and spleen may not be palpable; the kidneys are frequently palpable. The stomach may be palpable if it is full. The intestinal tract is palpable as fluid-
filled bowel loops that should be freely movable and nonpainful.
The normal urinary bladder is also palpable, movable, and non-painful.

Diagnostics

For venipuncture, position the kitten in dorsal recumbency with the forelegs drawn back toward the abdomen and the head and neck extended. Draw blood from the jugular vein using a 1-mL syringe with a 25- or 26-gauge needle. Slow aspiration of blood is essential to avoid collapsing the vein. A small volume (0.5 mL) of blood can be used for the most critical tests (BOX 2).Blood chemistry and hematology values for neonates differ from those for adults (TABLE 3 and TABLE 4); most values normalize to adult levels by 4 months of age.8–10 Urine is collected for chemistry, sediment, and specific gravity analysis by stimulating the perineum; cystocentesis should be performed with great care in the very young because the bladder wall is easily damaged and because umbilical vasculature may still be patent and can be traumatized.
Urine specific gravity is 1.020 or lower in the first few weeks of life; adult values are reached by about 8 weeks of age.11 A fecal sample should be examined for common intestinal parasites such as Giardia and Isospora spp and roundworms using zinc sulfate centrifugation, a direct saline smear, and a Giardia fecal antigen test. Kittens as young as 2 weeks may be treated with pyrantel pamoate (5 to 10 mg/kg PO every 2 weeks).
Flea infestations should be treated aggressively, as they can cause life-threatening anemia. Young kittens can be bathed in pet-safe shampoo followed by thorough drying and combing of the hair-coat. Water-based pyrethrin sprays labeled for use in kittens may also be used. Nitenpyram is labeled for use in kittens at least 4 weeks of age and weighing at least 2 lb (0.9 kg). Most other flea control products are labeled for use in kittens from 8 weeks.

How to Treat the Small and the Sick age, although, anecdotally, selamectin has been used in kittens as young as 6 weeks of age. Ear mite (Otodectes) infestations are best treated with topical ivermectin. One product (Acarexx, Boehringer Ingelheim) has been demonstrated as safe in kittens as young as 4 weeks of age.

Testing for FeLV and FIV is an important part of both wellness care and investigation of illness (TABLE 5). Recommendations for FeLV and FIV testing in kittens have been recently published and should be reviewed.
Necropsy is underutilized as a diagnostic tool for multicat environments such as shelters or catteries. Necropsy results may provide information necessary to save remaining littermates or a future litter. For the best results, the whole body should be submitted (refrigerated, not frozen) to a qualified pathologist. If necessary, freezing is preferable to autolysis.

Basic Therapeutics

Rapid identification of illness and prompt intervention are the keys to success when treating ill kittens. Often the exact cause of a kitten’s illness is not apparent at the time of presentation, and therapy must be focused on supportive care. Initial therapy may include supplemental warmth, hydration, glucose administration, and nutritional support. Awareness of physiologic differences between neonatal and adult cats is important, and information about these differences should be reviewed.
Severe hypothermia occurs when the kitten’s rectal temperature is <94°F (34.4°C) and is associated with depressed respiration, impaired function of the immune system, bradycardia, and ileus. Hypothermic kittens should be rewarmed slowly, over 2 to 3 hours or more, to a maximum rectal temperature that is age appropriate.
Warming too rapidly may cause increased metabolic demand, resulting in dehydration, hypoxia, and loss of cardiovascular integrity. An incubator or oxygen cage is a good way to accomplish rewarming, but hot water bottles and heating lamps can also be used with very careful monitoring. For severely hypothermic kittens, fluids warmed to 95°F to 98°F (35°C to 37°C) may be administered via the intravenous (IV) or intraosseous (IO) route (depending on age).

Never attempt to feed a hypothermic kitten, as aspiration pneumonia due to gastrointestinal hypomotility and regurgitation is a significant risk. Monitor closely for recurrence of hypothermia after rewarming.Clinical hypoglycemia occurs when the blood glucose level is <3 mmol/L (50 mg/dL) and is a common problem for sick neonates due to kittens’ immature liver function and rapid depletion of glycogen stores. Hypoglycemia may be caused by vomiting, diarrhea, sepsis, hypothermia, or inadequate nutritional intake.

Kittens with hypoglycemia will be weak and lethargic and may be anorectic. If the kitten is not hypothermic or dehydrated, periodically administer 5% to 10% dextrose orally by gastric tube at 0.25 to 0.50 mL/100 g body weight until the kitten is stronger and normoglycemic (FIGURE 5).

Then begin feedings of kitten milk replacer if a lactating foster queen is not available. Critically ill neonates may require a bolus infusion of 12.5% dextrose IV or IO (0.1 to 0.2 mL/100 g or more), followed by a constant-rate infusion of 1.25% to 5% dextrose in a balanced electrolyte solution to prevent rebound hypoglycemia. Hypertonic dextrose solutions should not be administered sub-cutaneously because tissue sloughing may occur.
Dehydration occurs easily in neonatal kittens with hypoxia, hypothermia, diarrhea, vomiting, or reduced fluid intake. Neonates have poor compensatory mechanisms and immature kidney function. Daily urine output in kittens 1 month of age is 25 mL/kg compared with 10 to 20 mL/kg in adult cats.

Neonates also have higher fluid requirements than adults for reasons such as higher total body water (about 80% of body weight, compared with 60% in adults), greater ratio of surface area to body weight, higher metabolic rate, and less body fat. Hydration status may be difficult to assess in the youngest patients.

Skin turgor is not always a reliable test of hydration for kittens younger than 6 weeks because their skin contains less fat and more water than adult skin. The kitten’s mucous membranes should be moist and either slightly hyperemic or pink. Pale mucous membranes and a decreased capillary refill time indicate at least 10% dehydration. Neonatal urine is normally colorless and clear; in dehydrated kittens, the urine may be darker with a specific gravity >1.020.

If the kitten is normothermic and not in shock or cardiovascular collapse, warmed subcutaneous (SC) fluids can be administered, although absorption is slow in young kittens. If there is no gastrointestinal dysfunction, warmed oral fluids may be given.
These approaches are especially useful in the youngest and small-est patients (younger than 4 weeks).

If the kitten is moderately to severely dehydrated and large enough to facilitate IV therapy, IV fluid administration is the most effective. A mini-set (60 drops/mL) is used with a fluid or syringe pump or a burette. The cephalic or jugular vein can be catheterized with a 24-gauge, ¾-inch or 22- gauge, 1-inch catheter. Lactated Ringer solution is ideal for rehy-dration because lactate can be used as an energy source and 1.25% to 5% dextrose can be added if necessary.
Warmed fluids may be given as a slow IV bolus of 1 mL/30 g body weight (30 to 45 mL/kg), followed by a maintenance infusion of 80 to 120 mL/kg/d (8 to 12 mL/100 g/d) plus any ongoing losses.11,16 It is important to monitor fluid therapy closely; it is easy to overhydrate young kittens due to their immature renal tubular function. Hydration status can be monitored by several methods, but weighing the kitten every 6 to 8 hours on an accurate gram scale is useful and easily accomplished. Serial packed cell volume/total protein measurements may also be used. Electrolyte and glucose status should be monitored.

If it is difficult to achieve IV access, an alternative route for administration of fluids must be employed. The intraperitoneal route should be used cautiously in neonatal kittens due to the risk of inducing peritonitis or damaging blood vessels. IO access using the trochanteric fossa of the proximal femur is the best alternative to IV access in larger kittens; blood, fluids, and medications can be administered in this way, particularly in kittens about 4 weeks of age and older.Use a 20- to 22-gauge, 1-inch spinal needle or 18- to 25-gauge hypodermic needle as a catheter. Flow rates of up to 11 mL/min can be achieved by gravity. Use of cold fluids, too large a volume in a short time, or hypertonic or alkaline solutions will cause pain. IV access should be established as soon as possible.

Complications of IO administration include infection, extravasation of fluids, and bone and soft tissue trauma. Practical considerations, such as tolerance of stress, may dictate the use of SC fluid administration, at least initially. Careful monitoring of fluid absorption is required when the SC route is used.
Blood transfusions may be necessary in some sick neonatal kittens, particularly those with anemia due to fleas or intestinal parasites. Indications for blood transfusions are weakness, tachy-cardia, pale mucous membranes, and a hematocrit <15%. Blood from a compatible typed donor is diluted 9:1 with a citrate anticoagulant and given using a millipore blood filter via the IV or IO route at a rate of 20 mL/kg over a minimum of 2 hours.

Immunity

Kittens receive almost all their passive immunity during the first 18 hours of life (before gut closure) with the ingestion of colostrum; there is little or no transplacental transfer of immunoglobulins in cats.17 The serum IgG nadir is reached at about 4 weeks of age due to catabolism of maternal IgG and correlates with a period of vulnerability to infection ( FIGURE 6). IgG levels then steadily increase as the kitten’s own adaptive immunity develops.

Failure of passive transfer can occur in kittens that have not ingested colostrum during the first critical hours. Correction of failure of passive transfer can be accomplished by SC injection of serum from an adult cat with a compatible blood type that has been screened for infectious diseases. The only study in the literature used 15 mL/100 g body weight, divided into three doses over 24 hours.18 The minimum amount necessary is unknown.
Kittens with uncorrected failure of passive transfer start to produce IgG at about 4 weeks of age; they are therefore most vulnerable to infection from birth to at least 4 weeks of age.

Cystic Endometrial Hyperplasia/Pyometra Susan Little DVM Diplomate ABVP (Feline) Bytown Cat Hospital Ottawa, Canada

a) Etiology:

It has typically been believed thatbecause cats are induced ovulators, the incidence of cystic endometrial hyperplasia(CEH)/pyometra is lower than in dogs.

However, recent studies have shown a great many catsare also spontaneous ovulators, and therefore may experience prolonged diestral periodswithout pregnancy.

Repeated pseudopregnancies may predispose the uterus to CEH, which isa disorder of proliferative and degenerative changes in the endometrium associated with aging.Most queens with pyometra were in estrus some time in the preceding 60 days.

Potter et al(1991) reported that 40% (16/40) of queens with pyometra or endometritis had CLs. Lawler et al(1991) reported that 67% (20/30) queens with pyometra had luteal phase ovaries.

Progesterone causes hyperplasia of the endometrium and endometrial glands.

Other effects ofprogesterone include inhibition of local leukocyte responses to infection in the uterus anddecreased myometrial contractility.

Estradiol causes an increase in the number of estrogen andprogesterone receptors in the endometrium. It also causes cervical dilation during estrus andtherefore allows bacteria that are part of the normal flora of the vagina (especially E. coli andStreptococcus spp) to ascend into the uterus.

It is normal for cats to have both aerobic andanaerobic bacteria in the vagina.

Younger cats have more vaginal bacteria than older cats, andcats in heat or pregnant have more bacteria than anestrus cats.
Vaginal cultures are thereforehard to interpret since the queen has normal bacterial flora.

This combination of ascendingbacteria and an abnormal endometrium predispose queens to pyometra.

b) Clinical symptomsand diagnosis:

• Cats with CEH may or may not have endometritis.
• CEH tends to be a chronicsubclinical condition and may be hard to diagnose definitively without biopsy of the uterus.
• Apresumptive diagnosis of endometritis may be made from response to antibiotic treatment,which should last for 2-4 months.
• Uterine pathology, mostly secondary to CEH andendometritis, is common in queens over 5 years of age.
• CEH is very common in unbred queensover 3 years of age. Perez et al (1999) found that 88.2% of queens older than 5 years in abreeding colony had CEH, versus a 30% incidence in queens 2-4 years old.
• A group of feralqueens also sampled had no CEH.
• They concluded that colony queens showed a predispositionto CEH that was correlated with elevated serum estradiol concentrations.
• CEH is one of themost important causes of infertility in catteries.
• Cats with advanced CEH are occasionallyfound with mucometra or hydrometra, characterized by variable amounts of mucus in theuterus.
• In hydrometra, the mucin is thin and watery.
• In mucometra, the mucin is thick or evensemisolid.
• Queens with either condition do not have bacterial infections and are not systemicallyill.
• The main symptom is abdominal distension, with or without a vaginal discharge.
• Theclinical signs of pyometra include a vulvar discharge, depression, dehydration, anorexia, fever,weight loss and a distended abdomen.
• Any abnormal vulvar discharge in an intact queen shouldbe assumed to be due to pyometra.
• However, 15-30% of queens have no vulvar discharge(closed cervix).
• Queens are often very meticulous in grooming, however, so evidence of thedischarge may be hard to find.
• A surprising number of queens with open cervix pyometras havelittle or no signs of systemic illness.
• Very occasionally, pyometra is found during a routineannual health examination.
• Polyuria and polydipsia are far less frequent in queens withpyometra than bitches.
• Most queens with pyometra will have a leukocytosis with a left shift.
• Thediagnosis can be affirmed by finding an enlarged uterus on radiographs or ultrasound.
• In somecases, the uterine enlargement is segmental, mimicking a pregnancy.
• Occasionally, only onehorn of the uterus is involved.
• Cats who have CEH but not pyometra may be normal onphysical examination.
• Their blood and urine tests are normal.
• Ultrasound of the abdomen is very sensitive in detecting uterine enlargement.
• Radiographs are not as useful, but being able tosee the uterus on a radiograph usually indicates the uterus is enlarged. The final diagnosis isoften not made until exploratory surgery is performed and the uterus is removed and/orbiopsied.

c) Treatment:

• There is no specific treatment for CEH.
• Theoretically, a prolongedperiod of anestrus may allow for some normalization of the endometrium.
• Progestagens mustbe avoided.
• Mibolerone is effective in inducing anestrus in cats, but is associated with seriousadverse effects.
• Maintaining queens in less than 10 hours of daylight may induce a photoperiodanestrus.
• Initial treatment for pyometra may involve intravenous fluids and antibiotics.
• SinceE. coli is the most common bacterium involved, good antibiotic choices are enrofloxacin(Baytril®), trimethoprim-sulfa (Tribrissen®), or clavulanate-amoxicillin (Clavamox®).
• It is notusually necessary to perform a culture and sensitivity test on the uterine discharge.
• Antibiotictherapy alone for pyometra is not often successful.
  Douches using antiseptic or antibioticsolutions are also not effective.
• One series of 183 queens (Kenney et al, 1987) with pyometrafound an 8% mortality rate, most commonly associated with a ruptured uterus and peritonitis.

Two approaches to treatment of pyometra may be taken: ovariohysterectomy and prostaglandintherapy.

i) Ovariohysterectomy provides the most consistent results as the source of theproblem is permanently removed and cats recover quickly. For queens who are not valuable toa breeding program, this is probably the best choice.

ii) Prostaglandin therapy has been themost successful treatment for open-cervix pyometra where it is desirable to preserve the futurefertility of the queen.

• Success rates for return to fertility may be as high as 86%. ProstaglandinF2 (PGF2) has been used both for pyometra and for metritis postpartum.
• The best queensfor this therapy are under 6 years of age, in good health, and have no retained fetal material ifthey are postpartum (ultrasound is very helpful in determining this).
• PGF2 therapy iscontraindicated in queens with some medical conditions such as asthma.
• PGF2 therapyshould not be used if the queen is in poor condition or is critically ill.
• Careful assessment of thepatient is critical for ruling out conditions that could preclude the use of PGF2.
• For example, inrare cases, pyometra is associated with uterine torsion, a contraindication for PGF2 treatment.
• Treatment of closed cervix pyometra should only be undertaken with caution, and only inmedically stable, young and otherwise healthy queens.
• If the cervix does not open after a fewdays of therapy, or if the queen becomes ill, she should be spayed. Only natural prostaglandinis used since a dose has not yet been established for use of synthetic prostaglandins for thispurpose in the cat.
• Queens are treated with 0.1 mg/kg of dinoprost (Lutalyse) SC, once ortwice daily for 5-7 days.
• The main purpose of the PGF2 is to cause the uterus to contract andexpel its contents.
• The luteolytic effects of PGF2 seen in other species have not beendocumented in the queen.
• If the feline CL does responds to PGF2 , it seems to take severaldays of treatment to effect luteolysis.
• Queens need to be watched closely during PGF2 therapyand may be hospitalized for the part of each day which follows administration of the drug.
• Queens must be monitored for rising fevers, abdominal pain, or other symptoms of systemicillness or rupture of the uterus (which could lead to peritonitis).
• Monitoring with radiographs orultrasound may be needed in addition to blood counts.
• The rate of complications with thistreatment is very low.
  Side effects are noted often, usually within minutes of the injection, andwill be worse in the first 2 days.
• The contractile effects of PGF2 on the smooth musculature ofthe myometrium, GI tract, respiratory tract, and bladder account for these reactions.
• Commonside effects include restlessness, vocalizing, panting, vomiting, diarrhea, salivation, and intensegrooming of the flanks and vulva.
• These effects usually last only a few minutes, rarely lastinglonger than 15-20 minutes.
• The reactions become less obvious with each treatment. Usually by the fifth day, little or no side effects are seen. Antibiotics should be given throughout the courseof PGF2 therapy and for some time afterward.
• Queens should be followed up by theveterinarian one and two weeks following PGF2 treatment.
• The vaginal discharge shouldchange to a clear fluid by the seventh day following treatment. This clear discharge may last forup to 10 days.
• Most cats are back to normal 2 weeks after treatment.
• If a purulent or bloodydischarge is persistent, a second course of therapy may be necessary.
• Most queens will comeback into estrus within several weeks and they should be bred at the first opportunity.
• It may bevaluable to treat the queen with antibiotics during this estrus and into the first 4 weeks of anyresulting pregnancy.
• An antibiotic safe for use in pregnancy, such as amoxicillin/clavulanic acid(Clavamox®), should be chosen.
  Occasionally, a queen has a second episode of pyometraafter a pregnancy, but repeating the PGF2 treatment may still enable her to have a litter in thefuture.
• After treatment with PGF2, pregnancy rates of 71-86% have been reported.
• Davidsonet al (1992) reported recurrence of pyometra within 1 year in 14% of treated cats.
• Some cats(4%) will have subclinical generalized peritonitis associated with pyometra which may contributeto ongoing problems with ill health and eventually necessitate ovariohysterectomy.
• There are noreports of successful treatment of closed pyometra in the cat although in the dog the successrate is reported to be 34%.

by Susan Little DVM, Dipl ABVP (Feline)

Hyperthyroidism (also called thyrotoxicosis) is one of the most common diseases of the middle-aged and older cat. It is a multi-system disorder caused by an increase in the amount of thyroid hormones (T3 and T4) produced by an enlarged thyroid gland. It was first documented in cats almost 30 years ago but the cause of the disease has been elusive. Although the enlargement in the thyroid gland is caused by a tumor called an adenoma, it is non-cancerous.

The most common clinical signs of hyperthyroidism in cats include weight loss, increased appetite (although some patients have decreased appetite), vomiting, increased thirst and urination, hyperactivity, and diarrhea. The high levels of thyroid hormones can cause the development of heart disease, and these patients may have a heart murmur, difficulty breathing, high heart rate and arrhythmias.

Veterinarians will order a blood chemistry panel as well as a thyroid hormone (T4) level in cats suspected of being affected by this disease. It is important to evaluate the health of the other major organs, including the kidneys and heart in these patients. Typically, hyperthyroid cats may have elevations in their liver enzymes. Chest x-rays and cardiac ultrasound may reveal secondary hypertrophic cardiomyopathy. Generally, the cardiac changes will reverse when the hyperthyroidism is treated. In some cases, specific heart medication may be needed to stabilize cardiovascular health. In recent years, it has been recognized that many hyperthyroid cats have concurrent chronic kidney failure that is being masked by the effects of hyperthyroidism. It has also been found that treatments directed at curing hyperthyroidism in these patients could lead to a worsening of their kidney function.

Most hyperthyroid cats will have elevated levels of the thyroid hormone T4 in their bloodstream on a routine screening test. However, a small percentage of hyperthyroid cats will have normal T4 levels. If hyperthyroidism is still strongly suspected in these patients, a more sensitive test called the T3 suppression test can be performed to confirm the diagnosis. In this test, the cat is given seven oral doses of the thyroid hormone T3. Blood levels for both T3 and T4 hormones are checked before and at the end of the administration of the medication. In a normal cat, the administration of T3 hormone will cause the blood levels of T4 to drop by a negative feedback mechanism. In a hyperthyroid cat, the T4 levels will not decrease at all or will decrease very little. In this way, the veterinarian can distinguish between cats with hyperthyroidism and cats with other diseases with similar symptoms.

Once hyperthyroidism has been confirmed, there are several treatment options. They include treatment with radioactive iodine, surgical removal of the gland, and treatment with anti-thyroid medications. The initial choice of treatment is often guided by concern about the patient’s kidney function status. Some cats have detectable impairment of kidney function at the time of their diagnosis with hyperthyroidism, but many do not. It is difficult to assess kidney function accurately from routine blood testing in cats. Generally about 2/3 of the kidney function must be lost before routine blood tests will show any abnormalities. This has made it very difficult in the past to detect which cats with hyperthyroidism actually have concurrent kidney failure. However, Michigan State University has introduced a very sensitive test of kidney function in cats and dogs called the iohexol clearance test. In this test, a radiographic contrast agent called iohexol is injected intravenously and the rate at which the kidneys clear the agent from the bloodstream is measured. The test is carried out in the veterinarian’s office and a series of blood samples is sent to the MSU lab for analysis.

Since hyperthyroidism induces increases in blood pressure and blood supply to the kidneys, treating the disease will result in a drop in the blood supply to the kidneys. In a cat with kidney failure, this can cause a worsening of their kidney function in the few months after treatment for hyperthyroidism with either radioactive iodine or surgical removal of the gland. For this reason, patients with known kidney disease (either detected on routine blood work or with the iohexol clearance test) are often treated with anti-thyroid medications rather than surgery or radioactive iodine in an effort to preserve their remaining kidney function. Using medications allows the veterinarian better control over the concurrent kidney disease and may allow the patient to survive longer.

Anti-thyroid medications in current use in North America include propylthiouracil (PTU) and methimazole (TapazoleŽ). Although they are both effective in decreasing thyroid hormone levels, PTU is associated with more adverse effects than methimazole. Methimazole is better tolerated and safer for long-term use in the cat. Approximately 15% of patients will suffer from side effects when taking methimazole. These may range from poor appetite, vomiting, lethargy and skin disease to more serious problems such as bone marrow depression and liver toxicity. In most cats, the adverse effects are mild and transient and do not interfere with continued treatment. Methimazole is now available from compounding pharmacies in a transdermal gel for those patients that are difficult to pill. Transdermal gels are applied to the inner ear and the medication is absorbed across the skin. Simple precautions must be taken to avoid inadvertent absorption of the drug by the person administering the medication.

More recently, a drug called ipodate (OragraffinŽ) has been used to treat hyperthyroidism in cats. Cats with severe hyperthyroidism do not respond to treatment with ipodate as well as cats with mild disease. A study at the Animal Medical Center of 12 cats being treated with ipodate showed no side effects. However, only eight of the 12 cats showed a positive response to the drug and the beneficial effects may not last for more than a few months. This drug is most useful for short-term management of cats requiring medical treatment in preparation for surgery. Unfortunately, ipodate is expensive, generally costing about $1/day, and is difficult to obtain. This is another reason why it may not be a suitable drug for long-term treatment.

For hyperthyroid cats that are assessed with normal kidney function, surgery or radioactive iodine treatment are often recommended. Both these options provide a cure of the hyperthyroidism and avoid the need for life-long administration of medication. In areas where radioactive iodine treatment is available, it is usually the treatment of choice since this option avoids the risks of anesthesia and surgery. However, this is not a widely available treatment choice and veterinarians have become very skilled in surgical removal of the thyroid gland (thyroidectomy), making this an excellent option for treatment of hyperthyroidism in many cats.

In general, the treatment a cat receives for hyperthyroidism will depend on individual status, including heart and kidney function. Concern about kidney failure is a major determinant of the course of treatment and may eliminate radioactive iodine or surgery as an option. The advent of new kidney function testing makes it possible to assess each patient’s risk of kidney failure following treatment for hyperthyroidism.