Clinical Parasitology Summary For 2007
The clinical parasitology laboratory examined 681 canine and 341 feline fecal samples during 2007. All fecal samples were examined using the zinc sulfate flotation technique. One or more parasites were found in 13.5% of the canine and 20.3 % of the feline samples. A total of 1140 canine blood samples were examined for the presence of heartworm: 3.3% of the samples were positive for heartworm antigen (although the majority of these dogs were rescued from the Gulf states). A total of 85 feline blood samples from cats showing signs that suggested a heartworm infection were examined, and 4.7% were positive for antibody to heartworm.
Dogs
Giardia duodenalis and Isospora spp (now known as Cystoisospora) were the most commonly seen protozoan parasites of canines, while Toxocara and Trichuris vulpis were the most commonly seen nematodes. 86.5% of the dogs examined had no parasites seen in their feces, while 2% had more than one parasite in the feces. Table 1 shows the parasites identified from dogs by the clinical parasitology laboratory in 2007.
Toxocara canis, Ancylostoma caninum, Giardia duodenalis, and Isospora spp. were much more common in dogs under 1 year of age (puppies) than in older dogs. Dipylidium caninum was seen in only 1 dog this year, indicating that flea control in the VHUP dog population continues to be very good. Strongyloides stercoralis was found in 1 puppy this year. We have seen S. stercoralis at least once a year since 2004, before this we averaged only one case every 2 years.
Heartworm was seen in 37 of the dogs examined, the highest prevalence (3.3 %) seen in any of the previous 6 years. Based on a sample of the medical history forms from dogs visiting VHUP in 2005, about 80% of VHUP canine patients were on HW prophylaxis. Since it is likely that all the heartworm positive dogs were not on prophylaxis, the infection rate in unprotected dogs is about 16.2 %. 29 of the positive dogs were “Katrina” rescues (strays from Louisiana and Mississippi) while the other 8 were local dogs (4 from PA, 2 from NJ and one from MD). In 2006 no local dogs were found infected with heartworm.
Table 1 Parasites of Dogs
| Parasite |
Prevalence |
Parasite |
Prevalence |
| Giardia duodenalis |
4.9% |
Dipylidium caninum |
0.2% |
| Isospora ohioensis |
3.2% |
Taenia sp. |
0.2% |
| Toxocara canis |
2.1% |
Toxascaris leonina |
0.2% |
| Trichuris vulpis |
1.9% |
Capillaria bohemi |
0.2% |
| Isospora canis |
1.5% |
Sarcocystis sp. |
0.2% |
| Ancylostoma caninum |
1.3% |
Tritrichomonas canis |
0.2% |
| Strongyloides stercoralis |
0.2% |
Trematode (Alaria?) |
0.2% |
Cats
The situation in cats hasn’t changed much since last year, Toxocara cati was still the most common parasite of cats (Table 2). Cats under a year of age were more likely to infected with a parasite than older cats; 29.6% of kittens were infected vs 20.1% of older cats. Most of the cats examined belonged to students/staff and were usually recently adopted strays. If we consider only client-owned cats then 33.3% of the kittens had parasites vs 11% of cats over 1 year of age. We did diagnose 2 cases of Tritrichomonas foetus last year and one case of lungworm (Aelurostrongylus abstrusus).
85 cats, all of whom had symptoms which suggested to the clinician that the cat was infected, were tested for antibody and antigen to heartworm. None of these cats tested positive for antigens from heartworm, however 4 (4.7%) tested positive for antibodies to heartworm. While this may just indicate exposure to the larvae of Dirofilaria immitis, recent research indicates that even the larvae can cause a severe disease in cats.
Table 2. Parasites of Cats
| Parasite |
Prevalence |
Parasite |
Prevalence |
| Toxocara cati |
10.9% |
Dipylidium caninum |
0.9% |
| Giardia |
5.3% |
Tritrichomonas foetus |
0.6% |
| Isospora felis |
2.4% |
Aelurostrongylus abstrusus |
0.3% |
| Isospora rivolta |
1.2% |
Ancylostoma tubaeforme |
0.3% |
| |
|
Toxoplasma/ Hammondia |
0.3% |
Serology for Protozoal and Arthropod-borne Diseases in Dogs and Cats
A positive serology for Borrelia burgdorferi was seen in 17.2% of the tested dogs (Table 3). This is 3 points lower than last year and continues a trend of declining prevalence that has been seen over the last 3 years. Approximately 25% of the tested dogs were healthy blood donor dogs, but there was no difference in the prevalence of antibodies to B. burgdorferi between patient and blood donor dogs. The same applies to donor and patient dogs testing positive for Ehrlichia canis. Antibodies to Anaplasma phagocytophilum (aka Ehrlichia equi) were found in 5.6% of the dogs tested. The western blot for Bartonella spp does not distinguish between B. henselae and B. vinsonii, however based on positive samples sent out for typing all are likely to have been B. henselae. 72.2% of the Babesia canis positive dogs were greyhounds.
Table 3. Serology
| Disease Agent |
Number examined |
% positive |
| Borrelia burgdorferi (Lyme) |
1135 |
17.2 |
| Ehrlichia canis |
1135 |
0.9 |
Anaplasma phagocytophilum
(Ehrlichia equi) |
1136 |
5.6 |
| Rickettsia rickettsii (RMSF) |
267 |
1.9 |
| Bartonella spp. |
383 |
3.1 |
| Neospora caninum |
157 |
IgG 1.9
IgM 1.3 |
| Babesia canis |
315 |
5.7 |
| Babesia gibsoni |
9 |
0 |
| Hemobartonella felis (FIA) |
74 |
1.4 |
Clinical Parasitology: Summary of 2007 Findings
Dogs
Results for dogs under 1 year of age (N=179, 29.7% infected):
| Parasite |
Prevalence |
Giardia duodenalis
|
11.7% |
Isospora spp.
|
11.7% |
Isospora ohioensis
|
6.7% |
Isospora canis
|
5.0% |
Toxocara canis
|
5.6% |
Trichuris vulpis
|
2.8% |
Ancylostoma caninum
|
2.2% |
Dipylidium caninum
|
0.6% |
Toxascaris leonina
|
0.6% |
Strongyloides stercoralis
|
0.6% |
Tritrichomonas canis
|
0.6% |
Trematode (Alaria sp.?)
|
0.6% |
Results for dogs over 1 year of age (N=497, 7.6% infected):
| Parasite |
Prevalence |
| Giardia duodenalis |
2.6% |
| Isospora ohioensis |
2.0% |
| Trichuris vulpis |
1.4% |
| Ancylostoma caninum |
1.0% |
| Toxocara canis |
0.6% |
| Isospora canis |
0.2% |
| Sarcocystis sp. |
0.2% |
| Taenia pisiformis |
0.2% |
| Capillaria (Eucoleus) bohmi |
0.2% |
Heartworm was seen in 3.3% of 1140 dogs examined. However, approximately 80% of the dogs seen by VHUP last year were given prophylaxis during the transmission season. So since all of the positive dogs came from the unprotected population, the rate for this group would be 16%. An additional consideration with these positive dogs was the fact that 78% of the infected dogs were strays from Louisiana or Mississippi.
Clinical Parasitology: Summary of 2007 Findings
Cats
Results for cats under 1 year of age (N=135, 29.6% infected):
| Parasite |
Prevalence |
| Toxocara cati |
17.8% |
| Isospora spp. |
9.6% |
| Isospora felis |
8.9% |
| Isospora rivolta |
0.7% |
| Giardia duodenalis |
5.9% |
| Dipylidium caninum |
0.7% |
| Ancylostoma tubaeforme |
0.7% |
| Aelurostrongylus abstrusus |
0.7% |
| Tritricho monas foetus |
0.7% |
Results for cats over 1 year of age (N=199, 20.1% infected):
| Parasite |
Prevalence |
| Toxocara cati |
6.0% |
| Giardia duodenalis |
4.0% |
| Isospora spp. |
4.5% |
| Isospora felis |
3.0% |
| Isospora rivolta |
0.5% |
| Dipylidium caninum |
1.0% |
| Toxoplasma / Hammondia |
0.5% |
| Tritrichomonas foetus |
0.5% |
85 cats, all of whom had symptoms which suggested to the clinician that the cat was infected, were tested for antibody and antigen to heartworm. Four (4.7%) were Ab positive. All were Ag negative.