Annette Litster

Feline heartworm disease: a clinical review

Feline heartworm disease is caused by the filarial nematode Dirofilaria immitis, and is transmitted by mosquitoes in heartworm-endemic areas worldwide. While dogs are the definitive hosts for this parasite, cats can also be infected, and the overall prevalence in cats is between 5% and 10% of that in dogs in any given area. The spectrum of feline presentations varies from asymptomatic infections to chronic respiratory signs, sometimes accompanied by chronic vomiting to acute death with no premonitory signs. Ante-mortem diagnosis can be challenging and relies on a combination of tests, including antigen and antibody serology, thoracic radiography and echocardiography. As treatment with heartworm adulticidal drugs can be life-threatening and heartworm infection in cats is often self-limiting, infected cats are frequently managed with supportive treatment (corticosteroids, bronchodilators, and anti-emetics). Surgical removal of filariae using extraction devices may be considered in some acute cases where immediate curative treatment is necessary, but filarial breakage during the procedure may result in an acute fatal shock-like reaction. Necropsy findings are mainly pulmonary and include muscular hypertrophy of the pulmonary arteries and arterioles on histopathology. A number of safe and effective macrocytic lactone drugs are available for prophylaxis in cats. These drugs can kill a range of larval and adult life-cycle stage heartworms, which may be advantageous in cases of owner compliance failure or when heartworm infection status is undetermined at the time prophylaxis is commenced. An index of suspicion for feline heartworm disease is warranted in unprotected cats with respiratory signs, and perhaps chronic vomiting, in areas where canine heartworm disease is endemic. Many cats, once diagnosed and with appropriate supportive care and monitoring, will resolve their infection and be free of clinical signs.

Characterisation of the signalment, clinical and survival characteristics of 41 cats with mast cell neoplasia

Mast cell tumours (MCTs) are relatively common tumours of cats, and are the second most common cutaneous tumours in cats in the USA. While the primary splenic form of the disease is far less common, it is usually associated with more severe clinical signs. Signalment, clinical and survival characteristics of mast cell neoplasia were characterised in 41 cats. The most common tumour location was cutaneous/subcutaneous head and trunk. Stage 1a was the most common tumour stage at first diagnosis (n=20), followed by stage 4 (both stage 4a and stage 4b; n=10). Of 22 cats that underwent excisional biopsy, mast cell neoplasia recurred in four cats during the study period. Three of the 41 cats presented with simultaneous cutaneous and either splenic or lymph node tumours. A comparison between cats with only cutaneous tumours (n=30) and those with tumours involving the spleen or lymph nodes (n=11) showed longer survival times for the cutaneous-only group (P=0.031). Twelve of the 41 cats died of mast cell neoplasia during the study period. When a subgroup of cats with only cutaneous tumours (no lymph node or visceral involvement) were divided according to whether there were multiple (five or more) tumours (n=6) or a single tumour (n=19), cats with single tumours survived longer than those with multiple tumours (P=0.001). Solitary cutaneous feline MCTs without spread to the lymph nodes usually manifest as benign disease with a relatively protracted course. However, multiple cutaneous tumours, recurrent tumours and primary splenic disease should receive a guarded prognosis due to the relatively short median survival times associated with these forms of the disease.

Canine bacterial urinary tract infections: new developments in old pathogens.

Uncomplicated bacterial urinary tract infections (UTIs) occur commonly in dogs. Persistent or recurrent infections are reported less frequently. They typically occur in dogs with an underlying disease and are sometimes asymptomatic, especially in dogs with predisposing chronic disease. Escherichia coli is the organism most frequently cultured in both simple and complicated UTIs. Organisms such as Enterococcus spp. and Pseudomonas spp. are less common in uncomplicated UTI, but become increasingly prominent in dogs with recurrent UTI. The ability of bacteria to acquire resistance to antimicrobials and/or to evade host immune defence mechanisms is vital for persistence in the urinary tract. Antimicrobial therapy limitations and bacterial strains with such abilities require novel control strategies. Sharing of resistant bacteria between humans and dogs has been recently documented and is of particular concern for E. coli O25b:H4-ST131 strains that are both virulent and multi-drug resistant. The epidemiology of complicated UTIs, pathogenic traits of uropathogens and new therapeutic concepts are outlined in this review.

Occult bacterial lower urinary tract infections in cats - Urinalysis and culture findings

Bacterial urinary tract infections (UTIs) can be detected in feline urine submitted for urinalysis and culture as part of the diagnostic workup for a variety of conditions. Our aim was to investigate urinalysis and culture findings in urine specimens from cats with no history of lower urinary tract signs. Study inclusion criteria required cystocentesis specimens from cats with no history of lower urinary tract signs, inappropriate urination, or previous UTI (including pyelonephritis). Of 132 specimens, 38 were culture positive and 94 were culture negative. Culture positive urine specimens were more likely to come from older female cats (p=0.03, p<0.001, respectively) and they had higher pH (p=0.001), erythrocyte (p=0.013) and leukocyte counts (p=0.003) than culture negative urine specimens. Gram-negative infected specimens (n=15) had lower urine specific gravity and higher leukocyte counts than Gram-positive infected specimens (n=21; p=0.0012, p=0.005, respectively) and culture negative specimens (p=0.003, p<0.0001, respectively). Urine protein:creatinine ratio was higher in Gram-negative infected urine than in culture negative urine (p=0.013). Enterococcus faecalis was the most commonly isolated bacteria (19 of a total of 44 isolates; 43.2%) and E. coli phylogenetic group B2 was the most common Gram-negative isolate (14 of a total of 44 isolates; 31.8%). We conclude that feline bacterial urinary tract infections can occur in cats without lower urinary tract signs, particularly older females and that they are associated with high urine erythrocyte and leukocyte counts.

Feline bacterial urinary tract infections: An update on an evolving clinical problem

Although feline urine is increasingly submitted for bacterial culture and susceptibility testing as part of a more general diagnostic work-up for a range of presentations in veterinary practice, bacterial urinary tract infections (UTIs) are relatively uncommon due to a variety of physical and immunological barriers to infection. Culture positive urine is most often obtained from older female cats and the clinical history may include hematuria, dysuria and pollakiuria, or the infection may be occult. Urinalysis usually reveals hematuria and pyuria, and Escherichia coli and Gram-positive cocci are cultured most frequently. Most feline UTIs can be successfully treated using oral amoxicillin or amoxicillin/clavulanic acid administered for at least 14days, but the prevalence of antimicrobial resistance amongst infecting bacterial species is a growing concern. There is currently no conclusive information on the safety and efficacy of alternative therapeutic agents for the treatment of feline UTIs.

Comparison of the efficacy of amoxicillin-clavulanic acid, cefovecin, and doxycycline in the treatment of upper respiratory tract disease in cats housed in an animal shelter.

OBJECTIVE To compare efficacy of amoxicillin-clavulanic acid, cefovecin, and doxycycline in shelter-housed cats with clinical signs of upper respiratory tract disease (URTD). DESIGN Randomized prospective clinical trial. Animals-48 cats with URTD. PROCEDURES Conjunctival and nasal swab specimens were obtained for culture and susceptibility testing, and cats were randomly assigned to 3 treatment groups (16 cats/group) on day 1: amoxicillin-clavulanic acid (12.5 mg/kg [5.68 mg/lb], PO, q 12 h, for 14 days), cefovecin (8.0 mg/kg [3.64 mg/lb], SC, once), or doxycycline (10.0 mg/kg [4.55 mg/lb], PO, q 24 h, for 14 days). Oculonasal discharge, sneezing, coughing, dyspnea, demeanor, and food intake were scored twice daily for 14 days (scale, 0 [subjectively normal] to 3 [markedly abnormal]). RESULTS The most common bacterial isolates were Mycoplasma spp (n = 22) and Bordetella bronchiseptica (9). Cats treated with amoxicillin-clavulanic acid or doxycycline had significantly increased body weight by day 14. Cats that received doxycycline had significantly lower overall oculonasal discharge scores than those treated with amoxicillin-clavulanic acid or cefovecin. Cats treated with amoxicillin-clavulanic acid or doxycycline had significantly lower overall sneezing scores than those that received cefovecin. Cats that received amoxicillin-clavulanic acid had significantly decreased demeanor and food intake scores on day 2, whereas this was detected later in other groups (demeanor score on days 5 and 7 and food intake score on days 10 and 11 in the cefovecin and doxycycline groups, respectively). CONCLUSIONS AND CLINICAL RELEVANCE Oral administration of amoxicillin-clavulanic acid or doxycycline appeared to be more effective than a single SC injection of cefovecin in treating cats with clinical signs of URTD.

Tick toxicity in cats caused by Ixodes species in Australia: a review of published literature.

Tick toxicity in cats caused by Ixodes holocyclus and related species is a common medical condition on the east coast of Australia. Intoxication typically causes a flaccid ascending neuromuscular paralysis and clinical signs can include anxiety, dysphonia, hind limb weakness and/or ataxia, pupillary dilation, respiratory signs and possible bladder voiding dysfunction. Diagnosis is made with a combination of appropriate clinical signs and visualisation of tick(s) on a thorough body search. Cases are classified clinically using a scoring system, which grades neuromuscular weakness and respiratory compromise. The mainstays of treatment are tick removal, administration of tick antitoxin serum and intensive supportive care. Given a prompt and appropriate management regimen, prognosis is good, according to available literature. Most of the literature concerning tick toxicity in cats is anecdotal in nature and an evidence-based review of what is known of this condition has not previously been published.

Accuracy of a point-of-care ELISA test kit for predicting the presence of protective canine parvovirus and canine distemper virus antibody concentrations in dogs

Canine parvovirus (CPV) and canine distemper virus (CDV) are highly infectious and often fatal diseases with worldwide distributions, and are important population management considerations in animal shelters. A point-of-care ELISA test kit is available to detect serum antibodies to CPV and CDV, and presumptively to predict protective status. The aim of this study was to determine the diagnostic accuracy of the test compared to CPV hemagglutination inhibition titers and CDV serum neutralization titers determined by a reference laboratory, using sera collected from dogs housed at animal shelters. The ELISA test was used under both field and laboratory conditions and duplicate specimens were processed using an extra wash step. The test kit yielded accurate results (CPV: sensitivity 92.3%, specificity 93.5%; CDV: sensitivity 75.7%, specificity 91.8%) under field conditions. CDV sensitivity was improved by performing the test under laboratory conditions and using an optical density (OD) meter (laboratory performed 94.0%; OD 88.1%). Point-of-care ELISA testing for serum CPV and CDV antibody titers was demonstrated to be a useful tool for determining antibody status when making decisions regarding the need for CPV and/or CDV vaccination and also in animal shelters for population management.

A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs

The aim of this study was to compare the effects of three diets with varying macronutrient and fibre contents on postprandial plasma glucose, triglyceride, free fatty acid, and insulin concentrations over a 12 h period in 12 healthy neutered lean dogs. Each diet was fed to each dog for 3 weeks in a three-period cross-over study. Plasma analyte concentrations were measured prior to and after a meal at the end of the third week of each period. Postprandial glucose concentrations for the moderate carbohydrate and fibre diet were 0.4-0.7 mmol/L (8-12 mg/dL) lower than for both higher carbohydrate diets (p≤0.02). Postprandial glucose, insulin, and triglyceride concentrations in some dogs did not return to baseline by 12 h after feeding of each of the three diets. These results indicate that the moderate carbohydrate and fibre diet warrants evaluation in diabetic dogs. Variables should be measured over at least 12 h after feeding to fully evaluate postprandial dietary effects on these analytes.

Prevalence of positive antibody test results for canine parvovirus (CPV) and canine distemper virus (CDV) and response to modified live vaccination against CPV and CDV in dogs entering animal shelters.

Canine parvovirus (CPV) and canine distemper virus (CDV) infections are relatively common in animal shelters and are important population management issues since the immune status of incoming dogs is usually unknown. This study aimed to determine the prevalence of positive antibody test results for CPV and CDV in incoming dogs aged ≥ 4 months and to measure antibody response over 2 weeks following vaccination with a modified live vaccine (MLV). Dogs aged 4-24 months entering an adoption-guarantee shelter (Shelter 1, n=51) and aged ≥ 4 months entering a limited admission shelter (Shelter 2; n=51) were enrolled. Dogs from Shelter 1 had been vaccinated with MLV at a municipal shelter 5 days before enrollment, whereas dogs from Shelter 2 had no known history of vaccination at enrollment. Sera were obtained on day 1, immediately prior to CPV/CDV MLV, and tested using an in-clinic ELISA kit to detect CPV/CDV antibodies. Dogs negative for CPV and/or CDV were retested at day 6-8 and those dogs still negative at day 6-8 were retested at day 13-15. Prior to CPV/CDV MLV on day 1, more dogs tested positive for CPV (Shelter 1 - 68.6%; Shelter 2 - 84.3%) than for CDV (Shelter 1 - 37.3%; Shelter 2 - 41.2%). On day 1, prior to MLV, all spayed/neutered animals tested CPV antibody-positive (n=17/102) and CPV antibody-positive dogs were older than serologically negative dogs (Shelter 1, P=0.0029; Shelter 2, P=0.0042). By day 13-15, almost all dogs were CPV antibody-positive (Shelter 1 - 97.9%; Shelter 2 - 100.0%) and CDV antibody-positive (Shelter 1 - 93.8%; Shelter 2 - 97.8%). MLV induces protective antibody titers against CPV/CDV in almost all dogs after 13-15 days.