Ontario Animal Health Network (OAHN)
Companion Animal Network Team
Veterinary Need-2-Know (N2K) Update – May-Aug 2024

OAHN fall survey and lab data: Key results

There were 85 survey respondents from 33 counties, including primary care, referral, emergency and mobile practices. Respiratory, GI and tick-borne diseases dominated the primary infectious disease concerns as usual, but there were also numerous reports of ringworm outbreaks, as well as numerous or unusual dermatitis / allergy cases. Increased reports of pets exposed to Anaplasma spp. were also reflected in the upward trends seen over the past year in lab data reported on CAPCvet.org; graphs of the Ontario data are available on OAHN.ca to illustrate seasonal patterns.

Do you see what eye see? In early summer 2024, many companion animal veterinarians reported young guinea pigs from commercial retail outlets in Ontario with bilaterial conjunctivitis, sometimes with respiratory signs. Given the likely common source, it is likely these guinea pigs had chlamydial conjunctivitis due to Chlamydia caviae.  An important differential is infection with C. psittaci, the cause of human psittacosis. The NEW OAHN C. caviae factsheet has more info.

Horse or zebra: Cancer or fungus? In early 2024, a cat that underwent surgery for suspected mammary carcinoma was ultimately diagnosed with cutaneous blastomycosis instead, secondary to trauma caused by a garden stake (not snake!).  The case is described in the latest AHL Newsletter.

Rabies update

The streak continues – raccoon-variant rabies has not been detected in Ontario for over a year, and fox-variant rabies has not been detected since 2018. The MNR’s 2024 rabies control operations are currently underway.

Nonetheless, as always, with summer came bats, and as of the end of August, over 56 cases of rabid bats have been detected across the province in 2024. Tragically, rabies was also diagnosed in a person in Ontario who had contact with a bat in the province.  While it’s important to beware of bats as rabies reservoirs, it is equally important to be kind to this amazing and ecologically critical creatures! Check out OAHN’s new N2K: Bats in Ontario resource for more information.

For more resources, see OMAFA’s recent veterinary advisory on rabies in Ontario.

FIP drugs update

In February, Health Canada approved access to remdesivir and compounded GS-441524 for the treatment of feline infectious peritonitis (FIP) through the emergency drug release (EDR) process. GS-441524 can also be accessed by US veterinarians as of June 2024.

There is also now published evidence to support the use of a shorter treatment course (42 days vs 84 days) in cases of wet FIP that show a favourable initial response. Read the synopsis of the results, or the full study (Zuzzi-Krebitz et al. 2024).

Check out the NEW! OAHN podcast: FIP treatments (and where to find them) with special guest Dr. Kelly St. Denis for tips on using and accessing these drugs.

Changes to US dog import rules, AGAIN

It has been a rollercoaster ride over the summer trying to determine what the new rules will be for dogs travelling to the US from different countries, including Canada.  The first version of the rules was announced in May, followed by a number of changes in June and July ahead of the August 1 effective date, which included some detailed record requirements aimed at proving where the dog had been living for the last 6 months prior to entering the US. Then on July 22, the US CDC suddenly announced they were dramatically reducing the requirements for dogs coming from low-risk countries for dog-mediated rabies, like Canada.  Here’s what stuck – All dogs must:

• Be at least 6 months old
• Have a microchip (readable by a universal scanner)
• Appear healthy on arrival
• Have a CDC Dog Import Form receipt

The requirement for a current rabies vaccination certificate for dogs coming from Canada has been dropped – for now. But remember that dogs returning to Canada will still require proof of current rabies vaccination, even if they have only visited the US. Canada’s Minister of Health (Hon. Mark Holland) confirmed that the US has agreed to a nine-month grace period while Canada and the US find a workable, permanent solution that will minimize disruption to Americans and Canadians crossing the border with their dogs.  The CVMA has advocated for the involvement of both a CVMA and AVMA representative in future negotiations.

Mpox in animals: Good news, bad news

In May 2022, an outbreak of mpox (formerly known as monkeypox) began, which ultimately resulted in over 87 000 human cases in 110 countries. Prior to this, this zoonotic disease occurred primarily in central and west Africa. African rodents are the most likely reservoir of the virus, but information on susceptibility of other animal species is very limited. Good news: A US study has just been released that tested 24 dogs, 9 cats and 1 rabbit from households with at least one human mpox case in 2022-2023. They found no evidence of infection in any of the pets, though some of the pets were contaminated with virus from the infected humans.

A new outbreak of mpox caused by the clade I MPX virus is now spreading in 2024, which differs from the clade IIb MPX virus that caused the 2022 mpox outbreak. Bad news: As we cannot be certain that the two clades will behave the same way in other species, despite encouraging results from the study described above, the same precautions as before are recommended for avoiding animal  contact, and for managing pets that may have been exposed to infected humans.

• Treat pets like a human member of the household by avoiding close contact as much as possible, covering (human) skin lesions and practicing good hand hygiene when handling the pet or anything in its environment. Keep exposed pets indoors as much as possible.
• Preventing exposure of rodents, especially wild rodents, is particularly important, in order to avoid introducing the virus to the wildlife population where it could create a reservoir.

Stay alert: H5N1 flu, cows, cats, mice

Since it was first detected in US dairy cattle in March, H5N1 highly pathogenic avian influenza (HPAI) has been found in over 200 dairy herds in at least 14 US states.  It has yet to be detected in dairy cattle or dairy products in Canada, and no additional affected poultry premises have been detected in Ontario since last winter.  But make no mistake, the virus continues to circulate in wild birds in North America, and with the fall migration season upon us, vigilance remains critical.

Cats and rodents on affected US farms appear to be at increased risk of infection. The companion animal and wildlife OAHN teams, along with CWHC, continue to collaborate on a joint pilot project on H5N1 influenza in primarily outdoor / feral cats.  Visit the project webpage for details on case eligibility, sample collection and submission.

A recent series of H5N1 cases in cats from Colorado included two “indoor” cats with no clear exposure to known sources of the virus, which highlights the ongoing gaps in our current knowledge of how this virus may be transmitted and spread.

Veterinarians are encouraged to keep H5N1 infection in mind for any cat presenting with severe acute neurological or respiratory signs or sudden death, especially (but not exclusively) if they have potential contact with other infected animals in the area (e.g. birds, cattle, rodents).

Not-so-tropical mite

While mite infestations are quite common in many species, a specific diagnosis is not always pursued (or even necessary), as most uncomplicated mange will respond to the same type of treatment.  But sometimes when we look more closely, we find unexpected things, like one Toronto veterinarian who submitted samples for testing from a mangey rabbit that was infested with tropical rat mites (Ornithonyssus bacoti).

While they sound exotic, these mites are found globally in tropical and temperate regions, typically on wild rodents, but occasionally infecting managed breeding or research rodent colonies.  Heavy infestations can cause anemia, alopecia and pruritis in animals. These mites are also zoonotic, causing rat mite dermatitis in people.

Rabbits are an unusual host for O. bacoti. The rabbit in this case was treated, but the finding pointed to a potentially significant rodent problem in the building where it lived, which was referred to the local public health unit for further investigation.

Update: Lyme disease infographic

OAHN has once again updated its infographic for veterinarians on ticks and Lyme disease in Ontario with the latest risk area map for Ixodes spp. ticks from PHO.  It also has quick tips on monitoring, screening, and when not to treat dogs. Also check out the OAHN tick checklist for pet owners!

Help us help you!

Have an idea for an infographic you’d like to see, or a podcast you’d like to hear? Email oahn@uoguelph.ca to let us know!